**2. Improving relevant winemaking aspects by genetic manipulation**

The traditional ways of genetically manipulating yeast include gene deletion, gene overexpression under the control of heterologous promoters or the introduction of foreign genes [5]. The latter can be done using plasmids (both single or multicopy) or seeking a more stable chromosomal integration. Many different systems for modifying chromosome sequences inside cells have been created. A PCR-based gene targeting approach, that uses exogenous DNA introduced into the cell through various transformation methods, has become one of the most widely used. Selectable markers, sometimes involving antibiotic resistance are needed for validation and maintenance of integrated sequences. To eliminate those markers, scientists used a marker recycling approach that takes advantage of site-specific recombinase technologies. loxP-mediated Cre recombinase is a good example of this method [6]. Many characteristics of wine strains of *S. cerevisiae* can be improved by gene manipulation. We will focus on stress tolerance, nutrient optimization, sensory improvement and health enhancement.
